This invention concerns a printed and embossed material, suitable for use as a floor covering, and a method and apparatus for making it in a continuous process. More particularly, it concerns a multilayered material combining a base layer, a printed layer and a wear resistant layer, which is embossed in register with the print.
Reverse printed laminates have been made by laminating separate sheets of calendered base material and a preprinted plastic film. In continuous processes, the printed designs have been limited to random prints because of the difficulty of maintaining the desired dimensions in the preprinted plastic film, in the laminate and in some cases in the base material. The plastic film tends to stretch when it is being printed and subsequently dried. Since it is necessary to apply tension to the printed film during lamination in order to eliminate trapped air and wrinkles, the printed design can also be distorted during lamination.
Alternatively, tiles can be formed in batch processes with designs that are in register to the cut tile by laminating preprinted plastic sheets of silk screen designs on a suitable base material. The tiles can then be hand clicked from the sheets. The high cost of such a batch process makes in-register printed tile quite expensive and limits its acceptance.
An additional complication is imposed by the desirability of providing a textured surface by embossing the tile. Because the embossing step can be another cause of distortion, some processes are limited to embossing of a plastic surface layer that is integral with a nonplastic stable substrate such as asbestos or asphalt-saturated felt.
Alternatively, as described in U.S. Pat. No. 4,312,686, which is incorporated herein by reference, the distortions which occur during printing and laminating are minimized by printing the design on a stable base, preferably release paper, and then transferring the printed design to a hot plastic web made continuously by an extruder. A stress relieved hot plastic film is then laminated to the printed web to provide a protective wear coat. To emboss in register with the printed design, the laminated product is first aligned by means of registration marks that are printed along with the design. Embossing is then made using a conventional engraved roll having raised sections which are images of the printed design. After embossing, the web is partially cooled and annealed. It is then aligned with a die cutter using the same registration marks as used for alignment during embossing. As a result, individual tiles are cut automatically in register to the printed and embossed pattern.
Although the method described in the '686 patent is operative, the method does not, however, result in a vivid and sharp coloring of the tiles which is characteristic of true ceramic tiles. Such a simulation in color characteristics is not possible using the method disclosed in the '686 patent because of the particular method used in applying a decorative design to the tiles. In the '686 patent, a decorative ink design, which has been preprinted on a release paper, is transferred to the base web using transfer rollers which press the preprinted release paper onto the web. However, because the base web is not completely smooth, some of the print on the transfer paper never contacts the base web and remains on the release paper. As a result, the printed designs of the tiles which result from the method of the '686 patent frequently have a grainy appearance so that the coloring of the tile is not brilliant enough to simulate that of a ceramic tile.
In addition, because of the number of operations that are to be performed in the continuous production line disclosed in the '686 patent, a malfunction in any operation will stop the entire production line.